Requested by Girl_Goat_Ganyu

Marcus being your sibling includes:

Both of you escaping the parties Aro likes to host.

You hiding his house shoes when he makes you mad.

   - He changes the Wi-Fi password until you give them back

Both of you making fun of Aro or Caius.

You playing Rock, Paper, Scissors to see who has to help Aro when Aro needs help with something.

"You ask him!"

   - "I asked last time you ask him."

"I couldn't possibly say that!"

   - "But I can!"

   - Cue Marcus clamping a hand over your mouth and dragging you away