Appearing in "Battle Lines"
- Ms. Marvel (Carol Danvers) (Main story and flashback)
- Wonder Man (Simon Williams)
- Arachne (Julia Carpenter)
- Iron Man (Tony Stark)
- Prowler (Hobie Brown)
- Shroud (Max Coleridge)
- Unnamed agents
- Captain America (Steve Rogers) (Only in flashback)
- Rachel Carpenter (Mentioned)
- Mindy McPherson-Brown (Mentioned)
Races and Species:
- Ms. Marvel's Suit
- Extremis Armor
- Captain America's Uniform and Captain America's Shield (Only in flashback)
Synopsis for "Battle Lines"
The Civil War has begun and superheroes are forced to make a choice: register with the government or face incarceration. Ms. Marvel has chosen the former.
Ms. Marvel leads a S.H.I.E.L.D. team to arrest unregistered superhero the Prowler, also known as Hobie Brown. Their mission is a success and the team returns to base.
The next morning, Simon Williams visits Carol at her apartment, reminding her of their debriefing with Iron Man. They fly to Stark Tower and re-meet Julia Carpenter, now operating under the identity "Arachne." In the debriefing, Iron Man assigns their new missions: Arachne will go after Max Coleridge/The Shroud while Ms. Marvel and Wonder Man will search for the teenage superheroine Araña. Before Ms. Marvel leaves for her mission, Iron Man asks her about Captain America's whereabouts, and she claims she does not know.
Ms. Marvel remembers her earlier conversation with Captain America. He wanted her to support his anti-registration movement, but Carol had decided to register, claiming she was doing her duty as an American citizen. Cap says she is obeying an unjust law that disregards civil liberties, but Carol replies people are afraid and the Superhuman Registration Act will make them feel safer.
Meanwhile, at Ryker's Island, a S.H.I.E.L.D. agent interrogates Hobie Brown about who informed him of S.H.I.E.L.D. presence in his neighborhood. The agent even threatens Hobie's wife with incarceration and Hobie is forced to admit Arachne was his informant.
Arachne visits The Shroud, her boyfriend, at his apartment. The Shroud advises her to remain at Iron Man's faction lest her daughter will be in danger at the same time S.H.I.E.L.D. forces storm the penthouse. Although the Shroud claims Arachne was about to arrest him, Arachne chooses to help the Shroud escape, both becoming fugitives.
Later, after an evening of patrolling, Carol and Simon go to a fast-food restaurant to have dinner, the same restaurant Anya Corazon works at. A bunch of robbers attempts to attack the customers, but Carol and Simon neutralize them, just as Anya puts on her Araña outfit before them.
- Ms. Marvel enlists in the Civil War! Having advocated on behalf of the registered superheroes, Ms. Marvel takes a position training new heroes. Soon, a traitor is discovered and all hell breaks loose!