It’s unreal to me that Surtr actually has lore now, and also that we have learned a few more things about her personally:
Surtr skates. Her skateboard was a gift from her Rhodes Island colleagues to celebrate her 1st year anniversary of becoming a Rhodes Island employee.
Surtr’s copious consumption of ice cream was in part motivated by her eating it pissing off the actual Surtr, the Fire Giant she keeps trapped, because he hates it. He grows to lowkey like it.
Her insistence on not knowing how to use any Arts was partially true: She’s using the Fire Giant’s Arts granted to her by the swordstaff. This distinction is personally important to her because just as she owns many memories that do not belong to her, the Giant’s Arts are the same in that she can use them but they are not hers. Her mastery over the Giant’s Arts is not just instinctual, either, given her Base Skill is speeding up Guard Skill Mastery, suggesting she has in fact properly mastered these skills herself enough that she can teach others.
Surtr straight up just stole the Fire Giant’s name when she took the swordstaff and made the Giant submit to her. We don’t know her original name, if she had one, and neither does she.
Though she did originally hunt for the places where her memories took place to piece out which were hers and which weren’t, she eventually gave up because life at Rhodes Island was so fulfilling that she simply lost interest in piecing out a convoluted past in favor of enjoying a great present, making her the most wholesome identity thief I know.
Whatever it is she had going on, or perhaps just her raw willpower, likely a combination of both, allowed her to raw dog Surtr (Giant)’s possession, hit him with a No You, and she got a free sword out of it. This simply happened and we just have to live with it.