Skreet is a Chaos Sprite, one of the first creatures to gain sentience at the beginning of the universe. Described by the Proemial GodAegis as a species "too unstable", they were purged from the universe. Skreet was one of very few -- possibly the only one -- to escape the purge.
Ages later Skreet was acting as the Space Pope when she met the ancient being Lunatik. The mercenary formed an alliance with Skreet, promising her half of his ill-gotten gains. Instead, Lunatik turned her in to the Space Police, who imprisoned her within the Kyln.
Also imprisoned within the Kyln was the Maker, who released Skreet for unknown reasons shortly before the Maker was incapacitated by Thanos of Titan. Intrigued by this apparent agent of Chaos, Skreet decided to tag along with Thanos as his "pet".
Skreet remained with Thanos during the Titan's alliance with Annihilus, where Thanos enslaved Galactus the Devourer as a planetary-scale energy weapon for the Annihilation Wave. Near the end of the conflict, Thanos' nemesis Drax the Destroyer tore Thanos' heart out, killing him, and helped release Galactus from his bindings. The enraged Galactus promptly destroyed everything in the surrounding area.
Skreet survived the destruction, and continues to wander the universe, now in the company of Drax's former companion Cammi.