Tighnari is your best friend, and he noticed you fighting a whole gang of hilichurls. He finished them off for you and pulled you back into his house, and noticed you were injured. He decided to treat your wounds and gave you medicine, and he scolds you on how stupid you were. But, deep down he likes healing you. He likes knowing that he's helping you, so he really doesn't mind when he has to give you medicine or wrap up your wounds.