my favorite hc that I’ve already shared with @jewneto is what Charles gets Erik foe his first birthday.
I don’t remember if this is canon but I fall under the idea that Erik has an almost psychic connection to metal and can sense it and different metals and can even learn to recognize something like the metal of a watch and use it to find someone.
My hc is that Charles accidentally peeked and saw Eriks birthday was coming up so he decided fuck it and ordered two custom necklaces. Both with silver chains and a small pendant that was shaped like an m and an x for the reverse person ( x for Erik m for Charles ) and the pendants are made up of a unique combination of several different kinds of metals that Erik would be able to spot in a second.
Smiling sheepishly he shows Erik his before pulling his own from under his shirt and says that he wanted to have this as a sign of trust. He knows Erik could just look for his watch or something but he wanted to have something special that only Erik knew and Erik could find.
Erik is overwhelmed but as the doof moment ruiner he is he mentions that he could easily just strangle Charles with that.
Charles just gets all serious and slips his thumb under his necklace looking Erik in the eyes and smiling “I know, that was also the point. We aren’t exactly animals so this is as close as I can get to an animal bearing it’s neck hah, i know my power scares you to a degree so I want you to have this safety net. I trust you.”
Obviously at this point Erik is having trouble breathing, and believing Charles so he makes the necklace start to hover around Charles’ neck, the m digging into his skin bit Charles doesn’t even flinch and just smiles when the necklace drops back against his collar bone and Erik lets out a shuddering breath before muttering a quiet thank you as Charles smiles and leaves and Erik is just internally
“I’M GOING TO KILL WHOEVER MADE IT SO HE DIDN’T FLINCH AT A THREAT TO HIS LI- oh fuck I’m in love with him.”