Borrowed from Japanese ロリコン. The
控 (kòng) suffix — from English 'complex' via Japanese コン — productively forms fan-fixation labels in Chinese internet slang:
御姐控 (yùjiěkòng, fan of older-sister types),
制服控 (zhìfúkòng, uniform fetish),
兄控 /
妹控 (older-brother / little-sister fixation).