DC 10: Astrid is a punk rocker who does a couple gigs here and there in Freedom City.
DC 15: Astrid is an international student from Norway who's currently enrolled in Claremont Academy.
DC 20: Astrid's father disappeared without a trace when she was real young. Her mother recently died in a car crash.
DC 25: Astrid disappeared without a trace for several reported months after participating in a bar brawl that became deadly. When she resurfaced no formal investigation about her whereabouts was officially made and the original case file disappeared.
DC 10: Ms. Thursday is a new teen superhero whose been flying around Freedom City. She's crazy strong and uses a aluminium baseball or something that looks like one as a weapon.
DC 15: Ms. Thursday is one of the superhero students at Claremont Academy. Her tuition was paid for in literal golden coins from the Viking Age. Crazy, right?
DC 20: Ms. Thursday uses a magical club weapon called Porrklubba. She's somehow involved with the Norse gods.
DC 25: Ms Thursday is Astrid Torsten, a foreign student from Norway who came to Freedom City to train at Claremont Academy. So as long as Ms. Thursday is holding Porrklubba she has the power to fly, teleport, and even manipulate the weather. She's the illegitimate daughter of the Norse god Thor.
Knowledge [Arcane Lore]
DC 15: Ms. Thursday's weapon Porrklubba is covered in ancient Nordic runes that symbolize lightning, thunder and storms.
DC 20: Ms. Thursday is an Asgardian. Her weapon Porrklubba was crafted by the same smiths who made Mjolnir. Only Ms. Thursday can held it.
DC 25: Ms. Thursday is the bastard daughter of Thor, the Norse god of thunder. Despite being a demigoddess her reputation amoung the Norse pantheon is strained.