Connections
-Both are considered demons but not fully demon (Hellboy's half human and demon, and Charlie's the daughter of a fallen angel [Lucifer], who isn't a full demon)
-Both are kinda on bad terms with their dads (Hellboy has never met his real dad [Azzael] and Charlie has daddy issues)
-Both are royalty in Hell (Hellboy's father was a demon king, making him a prince of Hell [his mother was also the last descendant of King Arthur, making him royalty on both sides], and Charlie is the inherited princess of Hell)
-Both have a "Full Demon" transformation (Hellboy goes Full Demon when he wields Excalibur, and Charlie can just go Full Demon whenever)
-Both swear moderately (Watch the 2019 Hellboy movie and one episode of Hazbin Hotel and you'll know what I'm talking about)
Contrast
-Charlie cares about most people while Hellboy has a "I don't give a shit" attitude
-Hellboy will fight without hesitation, but Charlie usually avoids fighting
Battle Name: A Normal Day In Hell