"Annalise, listen carefully. You are not to get involved in trying to kill him. My family-"
"You made me the lady of the manor. Doesn't that make me part of your family or had I thought too far ahead and I should wait until there is a ring on my finger or my last name changed?" Annalise asked, genuinely confused as to if she was considered part of his family.
This was all new to her, but Annalise already saw herself to be part of his family. So when Travis poked at Rafael, River, or Beatrice, she was ready to attack to protect them. Why was it bad for her to join in killing Travis? It wasn't like she couldn't protect herself.
Annalise didn't want Rafael to always try to shield her from danger when she could help him. If it was up to her, Travis would have been dead the second he came to town so she wouldn't have to hear about him now. Their only concern would be the truce.