The creatures who hunt the young God down, tear him apart and devour his flesh raw aren’t Titans. It was Onomakritos who first called them that:

Those about the sanctuary say that the Mistress was brought up by Anytos, who was one of the Titans, as they are called. The first to introduce Titans into poetry was Homer, representing them as Gods down in what is called Tartaros; the lines are in the passage about Hera’s oath. From Homer the name of the Titans was taken by Onomakritos, who in the orgies he composed for Dionysos made the Titans the authors of the God’s sufferings. (Pausanias, Description of Greece 8.37.5)

The Titans were terrifying ancestral spirits who dwelt in the abyss of the underworld; thus a natural choice to play the part of villain in the myth he was stitching together from random Orphic fragments. Part of what may have inspired Onomakritos to take this artistic license is that the perpetrators of the deed smeared themselves with titanos, as Nonnos lets slip:

Zagreus the horned baby, who by himself climbed upon the heavenly throne of Zeus and brandished lightning in his little hand, and newly born, lifted and carried thunderbolts in his tender fingers for Zeus meant him to be king of the universe. But he did not hold the throne of Zeus for long. By the fierce resentment of implacable Hera, the Titanes cunningly smeared their round faces with disguising chalk (titanos), and while he contemplated his changeling countenance reflected in a mirror they destroyed him with an infernal knife. There where his limbs had been cut piecemeal by the Titan steel, the end of his life was the beginning of a new life as Dionysos. He appeared in another shape, and changed into many forms: now young like crafty Kronides shaking the aegis-cape, now as ancient Kronos heavy-kneed, pouring rain. Sometimes he was a curiously formed baby, sometimes like a mad youth with the flower of the first down marking his rounded chin with black. Again, a mimic lion he uttered a horrible roar in furious rage from a wild snarling throat, as he lifted a neck shadowed by a thick mane, marking his body on both sides with the self-striking whip of a tail which flickered about over his hairy back. Next, he left the shape of a lion’s looks and let out a ringing neigh, now like an unbroken horse that lifts his neck on high to shake out the imperious tooth of the bit, and rubbing, whitened his cheek with hoary foam. Sometimes he poured out a whistling hiss from his mouth, a curling horned serpent covered with scales, darting out his tongue from his gaping throat, and leaping upon the grim head of some Titan encircled his neck in snaky spiral coils. Then he left the shape of the restless crawler and became a tiger with gay stripes on his body; or again like a bull emitting a counterfeit roar from his mouth he butted the Titanes with sharp horn. So he fought for his life, until Hera with jealous throat bellowed harshly through the air–that heavy-resentful step-mother! And the gates of Olympos rattled in echo to her jealous throat from high heaven. Then the bold bull collapsed: the murderers each eager for his turn with the knife chopt piecemeal the bull-shaped Dionysos. (Dionysiaka 6.155 ff)

Eustathius lets us in on the secret when he remarks:

We apply the word titanos in general to dust, in particular to what is called asbestos, which is the white fluffy substance in burnt stones. It is so called from the Titans in mythology, whom Zeus in the story smote with his thunderbolts and consumed to dust. For from them, the fine dust of stones which has crumbled from excessive heat, so to speak Titanic heat, is called titanic, as though a Titanic penalty had been accomplished upon it. And the ancients call dust and gypsum titanos.

But it’s Clement of Alexandria who reveals the truth without fully understanding what he exhorts:

The mysteries of Dionysos are wholly inhuman; for while still a child, and the Curetes danced around his cradle clashing their weapons, and the Titans having come upon them by stealth, and having beguiled him with childish toys, these very Titans tore him limb from limb when but a child, as the bard of this mystery, the Thracian Orpheus, says:–

“Cone, and spinning-top, and limb-moving rattles, and fair golden apples from the clear-toned Hesperides.”

And the useless symbols of this mystic rite it will not be useless to exhibit for condemnation. These are dice, ball, hoop, apples, top, looking-glass, tuft of wool.

Athene, to resume our account, having abstracted the heart of Dionysos received the name Pallas from its palpitating (pallein). And the Titans who had torn him limb from limb, setting a caldron on a tripod, and throwing into it the members of Dionysos, first boiled them down, and then fixing them on spits, “held them over the fire.” But Zeus having appeared, since he was a God, having speedily perceived the savour of the pieces of flesh that were being cooked,–that savour which your Gods agree to have assigned to them as their perquisite, assails the Titans with his thunderbolt, and consigns the members of Dionysos to his son Apollo to be interred. And he–for he did not disobey Zeus–bore the dismembered corpse to Parnassus, and there deposited it.

If you wish to inspect the orgies of the Corybantes, then know that, having killed their third brother, they covered the head of the dead body with a purple cloth, crowned it, and carrying it on the point of a spear, buried it under the roots of Olympus. These mysteries are, in short, murders and funerals. And the priests of these rites, who are called kings of the sacred rites by those whose business it is to name them, give additional strangeness to the tragic occurrence, by forbidding parsley with the roots from being placed on the table, for they think that parsley grew from the Corybantic blood that flowed forth; just as the women, in celebrating the Thesmophoria, abstain from eating the seeds of the pomegranate which have fallen on the ground, from the idea that pomegranates sprang from the drops of the blood of Dionysos. Those Corybantes also they call Cabiric; and the ceremony itself they announce as the Cabiric mystery.

For those two identical fratricides, having abstracted the box in which the phallos of Bacchus was deposited, took it to Etruria–dealers in honourable wares truly. They lived there as exiles, employing themselves in communicating the precious teaching of their superstition, and presenting phallic symbols and the box for the Tyrrhenians to worship. And some will have it, not improbably, that for this reason Dionysos was called Attis, because he was mutilated. And what is surprising at the Tyrrhenians, who were barbarians, being thus initiated into these foul indignities, when among the Athenians, and in the whole of Greece–I blush to say it–the shameful legend about Demeter holds its ground?

Did you catch it?

Here’s a hint: it’s actually the same story.

The murderers of Dionysos were his protectors, the Korybantes. They were charged with guarding his body and instead they tore and devoured it.

Mind you, this may not have happened when he was a child. His name is Zagreus, after all – the Great Hunter.

The one who greatly hunts, as the writer of the Alcmeonis said Mistress Earth, and Zagreus highest of all the Gods. That is, Dionysos. (Etymologicum Gudianum s.v. Zagreus)

He’s the savage one who roams the night with his mailed priests:

Son of the Phoenician princess, child of Tyrian Europa and great Zeus, ruler over hundred-fortressed Crete—here am I, come from the sanctity of temples roofed with cut beam of our native wood, its true joints of cypress welded together with Chalybean axe and cement from the bull. Pure has my life been since the day when I became an initiate of Idaean Zeus. Where midnight Zagreus roves, I rove; I have endured his thunder-cry; fulfilled his red and bleeding feasts; held the Great Mother’s mountain flame; I am set free and named by name a Bakchos of the Mailed Priests. Having all-white garments, I flee the birth of mortals and, not nearing the place of corpses, I guard myself against the eating of ensouled flesh. (Euripides, Cretans fragment 472)

They are warriors performing a frenzied dance amid thunderous drums and clanging metal. Nonnos describes them thus:

Already the bird of morning was cutting the air with loud cries; already the helmeted bands of desert-haunting Korybantes were beating on their shields in the Knossian dance, and leaping with rhythmic steps, and the oxhides thudded under the blows of the iron as they whirled them about in rivalry, while the double pipe made music, and quickened the dancers with its rollicking tune in time to the bounding steps. Aye, and the trees whispered, the rocks boomed, the forests held jubilee with their intelligent movings and shakings, and the Dryades did sing. Packs of bears joined the dance, skipping and wheeling face to face; lions with a roar from emulous throats mimicked the triumphant cry of the priests of the Kabeiroi, sane in their madness; the revelling pipes rang out a tune to honour of Hekate, divine friend of dogs, those single pipes, which the horn-polisher’s art invented in Kronos’s days. The noisy Korybantes with their ringing din awoke Kadmos early in the morning; the Sidonian seamen also with one accord, hearing the never-silent oxhide at dawn, rose from their rattling pebbly pallets and left the brine-beaten back of the shore. (Dionysiaka 3. 61 ff)

A less poetic but no loss evocative account of them is provided by Strabo:

Pherekydes says that nine Kyrbantes were sprung from Apollon and Rhetia, and that they took up their abode in Samothrake; and that three Kabeiroi and three Nymphai called Kabeirides were the children of Kabeiro, the daughter of Proteus, and Hephaistos, and that sacred rites were instituted in honor of each triad. Demetrius of Scepsis says that it is probable that the Kouretes and the Korybantes were the same, being those who had been accepted as young men, or ‘youths,’ for the war-dance in connection with the holy rites of the Mother of the Gods, and also as korybantes from the fact that they ‘walked with a butting of their heads’ in a dancing way. These are called by the poet betarmones: ‘Come now, all ye that are the best betarmones of the Phaiakes.’ And because the Korybantes are inclined to dancing and to religious frenzy, we say of those who are stirred with frenzy that they are ‘korybantising.’

Clement has these frenzied daimones dancing protectively around Zagreus and then suddenly the Titans show up – really there was just one group. Vengeful Hera goaded them and in a fit of madness they turned upon the leader of their war-band, murdered him and ate his flesh. Dionysos comes back to life:

Furthermore, so that we might seem to go more deeply, the story says that the Giants found Bacchus inebriated. After they tore him to pieces limb by limb, they buried the bits, and a little while later he arose alive and whole. We read that the disciples of Orpheus interpreted this fiction philosophically and that they represent this story in his sacred rites. (The Third Vatican Mythographer 12.5)

He then freed them from madness:

The titanic mode of life is the irrational mode, by which rational life is torn asunder: It is better to acknowledge its existence everywhere, since in any case at its source there are Gods, the Titans; then also on the plane of rational life, this apparent self-determination, which seems to aim at belonging to itself alone and neither to the superior nor to the inferior, is wrought in us by the Titans; through it we tear asunder the Dionysos in ourselves, breaking up the natural continuity of our being and our partnership, so to speak, with the superior and inferior. While in this condition, we are Titans; but when we recover that lost unity, we become Dionysoi and we attain what can truly be called completeness. (Damascius, Commentary on the Phaedo 1.9)

 And they rejoined his army – which we get in a variant tradition related by Diodoros Sikeliotes:

The struggle having proved sharp and many having fallen on both sides, Kronos finally was wounded and victory lay with Dionysos, who had distinguished himself in the battle. Thereupon the Titans fled to the regions which had once been possessed by Ammon, and Dionysos gathered up a multitude of captives and returned to Nysa. Here, drawing up his force in arms about the prisoners, he brought a formal accusation against the Titans and gave them every reason to suspect that he was going to execute the captives. But when he got them free from the charges and allowed them to make their choice either to join him in his campaign or to go scot free, they all chose to join him, and because their lives had been spared contrary to their expectation they venerated him like a God. Dionysos, then, taking the captives singly and giving them a libation of wine, required of all of them an oath that they would join in the campaign without treachery and fight manfully until death. (Library of History 3.71.4-6)

I believe that they represent the core of the Furious Host,

That is no wonder; for ’tis Bacchus himself, the God of wine, and the captain and emperor of drunkards. He is crown’d with ivy and vine leaves. He has a thyrsus instead of a scepter; that is, a javelin with an iron head, encircled by ivy or vine leaves in his hand. He is carried in a chariot, sometimes drawn by tigers and lions and sometimes by lynxes and panthers. And like a king he has his guards, who are a drunken band of satyrs, demons, nymphs that preside over the wine presses, fairies of the fountains and priestesses. Silenus sometimes comes after him sitting on an ass that bends under his burden. (Andrew Tooke, The Pantheon representing the Fabulous Histories of the Heathen Gods and Most Illustrious Heroes)

And what’s more, I believe that the healing ritual he performed to bring them back to sanity is the one reenacted through enthronismos:

They are doing just the same thing as those in the rite of the Korybantes do, when they perform the enthronement ceremony with the one who is about to be initiated. In that situation too there is some dancing and playing around, as you know if you have been initiated. (Plato, Euthydemos 277d)

Because the first Bacchus is Dionysos, possessed by the dance and the shout, by all movements of which he is the cause according to the Laws (II.672a5–d4): but one who has consecrated himself to Dionysos, being similar to the God, takes part in his name as well. (Damascius, Commentary on the Phaedrus 1.171)

On attaining manhood, you abetted your mother in her initiations and the other rituals, and read aloud from the cultic writings. At night, you mixed the libations, purified the initiates, and dressed them in fawnskins. You cleansed them off with clay and cornhusks, and raising them up from the purification, you led the chant, ‘The evil I flee, the better I find.’ And it was your pride that no one ever emitted that holy ululation so powerfully as yourself. I can well believe it! When you hear the stentorian tones of the orator, can you doubt that the ejaculations of the acolyte were simply magnificent? In the daylight, you led the fine thiasos through the streets, wearing their garlands of fennel and white poplar. You rubbed the fat-cheeked snakes and swung them above your head crying ‘Euoi Saboi’ and dancing to the tune of hues attes, attes hues. Old women hailed you ‘Leader’, ‘mysteries instructor’, ‘ivy-bearer’, ‘liknon carrier’, and the like. (Demosthenes, On the Crown 259-60)

So it is just as if someone were to initiate a man, Greek or barbarian, leading him into some mystic shrine overwhelming in its size and beauty. He would see many mystic spectacles and hear many such voices; light and darkness would appear to him in alternation, and a myriad other things would happen. Still more, just as they are accustomed to do in the ritual called enthronement, the initiators, having enthroned the initiands, dance in circles around them. Is it at all likely that this man would experience nothing in his soul and that he would not suspect that what was taking place was done with a wiser understanding and preparation? … Still more, if, not humans like the initiands, but immortal Gods were initiating mortals, and night and day, both in the light and under the stars were, if it is right to speak so, literally dancing around them eternally. (Dio Chrysostom, Oration 12.33-34)

What you should take away from this isn’t that Dionysos was destroyed by monsters – it’s that he then turned around and made those monsters his friends. Also, that the Korybantes are sons of Apollon.