Critique my group of Main Characters?

The main story I'm focusing on right now is called "Storybook Heroes", about a group of 4 teenagers going on an adventure together as part of a coming-of-age celebration. I would like some critiques on the 4 main characters:

Liam Archibald: Liam Archibald
Kiera Farryn: Kiera Farryn
Egan Reinwald: Egan Reinwald
Leylla Larksong: Leylla Larksong

I know I don't have anything filled in for the backstories yet. Liam, Kiera, and Egan don't really have an interesting backstory - they just grew up in a boring farming village, but I am working on Leylla's backstory.

Liam- Okay, he's a great guy! He seems really kind, strong, and very leaderlike. You should give him some flaws though.

Kiera-Does she have any soft spots? Does not have to be a flaw just something that is a secret or something that means a lot to her. I'm guessing it's her friends. Soft spot does not just have to be someone or something, it could be a strength that is hidden and people don't see right away.

Egan-Flesh him out a bit more. I don't know anything about him other than his outer self.

Leylla-Same as what I said about Egan.

Your characters have a good tried and true base. You just need to make them human and interesting besides what they seem to be like. Understand them from the inside. Figure out their values and views on stuff like death, life, religion, politics, etc. etc.

Hope this helped! If you have any question, ask! I'm happy to help. :)

I originally had more for Liam, Egan, and Kiera that fleshed them out more and revealed some of their "deep dark secrets", but I couldn't find any way at all to talk about it without also mentioning Leylla's death, since that stuff doesn't really come up until after she's dead.

This profiling stuff is for your own information, right? So you could write whatever you want here. When you're putting stuff in the story though, I guess you will have to figure it out. Maybe you could leak some stuff throughout the story without your readers really knowing what's going on but later they'll get it.