(in the Marvel universe) Lilly is the human and poison is a symbyote (like Venom and Eddie). Lilly was born into Aqua (Norwegian Hydra) and was experimented on; her last memory was (age 13) waking up in a med bay in Aqua (now has the eye thing and ability to ignite her body so hot the flames are blue, also that dark eye isn´t an eye, its a socket. I´ll explain why there´s a ´pupil´ in a sec). A year after that she has the name ´flame´ bc her ability; Lilly/Flame escapes Aqua and rushes into a forest and meets poison, instantly bonding on a mental and molecular level. Poison is a mutant symbeote so she is able to catch on fire as well, BUT because poison is still young (for a symbeote anyways) they are unable to do full body transformation (the thing when venom takes over Eddie's body like a shell, idk how to explain it). Now about the ´pupil that isn´t a pupil´, that is an orb of energy from poison. Whenever the 2 are separated they break down entirely.