She stabs herself with a "happy dagger".
A round character is a character we know mostly about, so an example of a scenario would be:
There was once a young girl named Sally, she is very tall, with brown eyes and dark black hair. She loves chocolates but hates sushi. But the one thing she loves the most is her sister Chey
Love is the answer you are looking for. Orsino is in love with Olivia. Olivia is in love with Cesario. Viola is in love with Orsino. Therefore your answer is Love.
(This is about a tiger, haha)
Its claws were so sharp, so they realized it's too dangerous to risk their lives to approach the tiger.