Showitious, or rather hyperfixation, was a term made by Fanfictiondreamer in which someone, mostly an autistic, has characters intruding/living in his/her mind randomly, rent-free, and hardly leaves! An obsession that seems to overwhelm her mind, as does Ikran's, Simply put, these are the characters TheIkranRider has encountered throughout her life; as part of her Autism, those characters would always stay within her mind, and she could never let go of them no matter how badly she wanted to. By writing fanfics or creating art or countdowns, these characters became special parts of her stories and projects she has written and developed as a way to help cope with it.

For more intel here's a link on hyperfixation, and intrusive thoughts.