After you defeated Brimscythe, just before his death he called you out, deciding if he can't kill your group he might as well break your trust in each other apart in the most devastating way he can think. Forcing you into giving your friends the truth about your history

"You... INSECT!.. You're one of us! We are ashamed of you! You Vermin! Brimscythe roared out his last few but definitely devastating words at you just before Grog cuts down his open wound right on his body killing Brimscythe

"Wh-Wait-What did he just say?" Scanlan confusingly looks while whipping around to look at you

"You vermin?.." Grog responds with an unreliable answer as per usual, also turning to look at you

"No... "You're one of us.." " Vex (the female elven twin) quotes also turning to look at you with a suspicious look

"What did that dragon mean?!" Percy or Percival marches up to you with a glare but Vax (the male elven twin) cuts of his path also looking at you, giving you the chance to explain before violence breaks out while Pike and Keyleth looks at you with worry, concern, and confusion

They're your friends.. You didn't lie.. You were a strong person who REALLY loved shiny objects.. Like a dragons amount of love for shiny treasuries.. Just didn't tell the entire truth about yourself.. Because you wanted to remain with your friends in hopes they didn't find out the truth and turn you away out of fear or discomfort.. (You're also in a human form obviously. Or elven or whatever you decide you're disguised appearance to be)