Tiki is an old dragon. She knew Marth. Fire Emblem Awakening takes place much, much later. Lucina gave the Avatar here a crown to make him resemble Marth.
Ah, Mar-Mar ❤️Tiki...Because you, too, are a singular - and very special - man to me. You are the man with whom I've...fallen in love.
From the Support Conversation (Rank S) between Tiki and MU