Sarah is a character played by Jane Le who appeared in The art of the heist.
In True friendship, the Dive Roll Adventurer's off-screen partner is named 'Sarah'. This page theorises that both sketches could be referring to same character.
"When Sarah and I get hitched, will you be my best man?" — Dive Roll Adventurer (True friendship)
Biography
Sarah was kidnapped by Fervante and held hostage in his mansion on Morningside Drive. She managed to escape, reunited with her heist team, and helped craft miniature banisters for Heath's model of Fervante's mansion. (The art of the heist)
Realising that Rick prioritised building the model over rescuing her, Sarah felt abandoned. At some point, she met the Dive Roll Adventurer, whose attentiveness towards feelings of abandonment led them to grow close and begin dating.
"Look, I know we only have an hour till Furfante kills Sarah, but that's still plenty of time to get the model right too." — Rick (The art of the heist)
"I don't want you to feel like you're like my second choice. Or to feel abandoned." — Dive Roll Adventurer (True friendship)