I doubt it would be by accident as well. Either a show to get their attention or she has something for them.
Sera: "I want to join your Inquisition"
Cassandra: "Give us a reason, elf. We are a professional organization, not some merry band of mistfits."
Inquisitor: "Actually, we are....."
Cassandra: "Shut it!"
Inquisitor: "Yes ma'am! Cassandra, ma'am!"
Cassandra: "Anyways, like I said, we don't just recruit anyone."
Sera: "I'm a proffesional archer, exceptional thief..... and I know alot of jokes!"
Inquisitor: "Hired! Welcome to the Inquisition!"
Cassandra: "Wait! Hold on a minute!"
Inquisitor: "I want you to tell me them all! We could really use someone with your skills!"
Sera: "Thank you! I shall do my best!"
Cassandra: "EXCUSE ME!"
Inquisitor: "Yes, what is it, Cassandra?"
Cassandra: "We are not going to hire her just because she knows good jokes!"
Inquisitor: "Oh please, stop beign such a stick in the mud. You can have her archery and I'll have her jokes!"
Cassandra: "But, but!"
Inquisitor: "Men! Let's move out!"
Cassandra: "........"
Sera: "Nice to meet you!"