Character Analysis
The other young terrorists aren't fleshed out in quite as much detail, but we get the sense that mostly, they're teenagers who signed up for a cause. It sounds like many of them had very little money or education, and may have become terrorists either out of a genuinely idealistic effort to help people who'd been treated unjustly, or possibly because they had no good options within their society.
Beatriz, the only girl among them besides Carmen, seems to be quite a contrast to Carmen. She's more interested in shooting dice with the guys than hanging out with Carmen and Roxane (6.3) and she seems to be less idealized as a character. She listens in on Oscar Mendoza's confession, for instance, although she does seem somewhat interested in being forgiven when Father Arguedas talks to her (though that's partially because she thinks he's kinda cute).
He also tells her to be kind and helpful as part of her way of repenting of her sins (8.118-146). Possibly as a result of that experience of confession, Beatriz doesn't turn Carmen in later, even though she finds out Carmen is smuggling Mr. Hosokawa into Roxane's bedroom, which could get her in pretty big trouble (8.180-192). Thanks for having their backs, Beatriz.
The rest of the terrorists' characters are less fully explored in the book, but it's easy to feel sad when they die because the book does show them becoming part of a community with their hostages. You don't have to think their choices were right to feel what a tragic loss it is for all these teenagers to die, and to wish they had found a different path for their short lives.