I thought of a better power (not necessarily better, but something I can work with) and a partial backstory.
Picture this: A young boy of 5 has his quirk reveal itself whilst playing a game of tag with his kindergarten class; when he is tagged as "it" the other child's hand becomes glued to "Sticky's" back. The child desperately tries to free his hand, but slowly he becomes absorbed by Sticky; other children try to help, but then all of a sudden, skin from Sticky starts grafting onto those children as well, absorbing them too. Their cries of terror reach the faculty members; and while they try and use their quirks to help the children escape from Sticky (who is also terrified by the way) they become absorbed too. His quirk ability would later be dubbed as: Sinew. Those children and adults became a part of Sticky's body, not dying but pretty much brain dead. After the first incident he became a 2.5 metre tall man-child, weighing in at 120 kg. His power's main applications are that he can use the added muscle and skin for: super strength, extending his reach and the size of his limbs (very grotesque by the way (I mean like body parts are just sticking out everywhere)), covering surface wounds (nothing can be done about organs and muscle, but he's got plenty to spare), and sometimes letting his quirk's absorption power activate. Some side effects include the real world application of him gaining the accumulated weight and size of his victims, needing to chop off pieces of himself that die (including organs that reach the surface), and needing to consume a large number of calories to function. The skin and protruding body parts he absorbed from his victims wrapped themselves around him, making him too ugly for the public eye (thus he has to wear super-heavy clothing all over his body not only to keep his power in check, but also to not be judged). This horrible curse caused unwanted media attention and hatred, the ramification being his parent's abandoning him on the streets. He then had to fend for himself until being taken in by the homeless. Nine years later he begins committing crimes with other homeless quirk users and villains, blaming the world for his circumstances. Unfortunately, (for reasons I will come up with later) that same crew kills much of the homeless population, sending him into a fit of rage and unleashing his quirk again. At this point he is 6 metres at 314 kg. It was then he made a promise to rid his city of villainy, enter Hero Academia, and make the streets safe for the homeless again.
