You could argue that of all the members of Team Voltron, Pidge is one of the more curious. While at first he seemed like a simple tech genius who wanted to find his captured father and brother, he...turned out to be a she.
Yes, Pidge....is a girl. Spoilers!!!
You see, Pidge's father, along with her brother Matt, were captured along with Shiro by the Galra. When Pidge found out about this, the entire Federation deem this an "accident" by pilot error. Pidge investigated and found out this wasn't true, and she stated that she wouldn't give up until she found them. Furious at what she had done, she was branded as a "threat" and thus wasn't allowed back into the base, or the academy, for any reason.
Because of this, she cut her hair, to the looks of her brother, and became Pidge Gunderson. All the while keeping a low profile so she could find out more about her father and brother's location.
Her drive to find her family is so strong that she often puts the need to get that information about her own safety, or the safety of Team Voltron. In fact, she even almost quit the team twice because of her desire to find out about her family.
Eventually though, Pidge came around, and stuck with the team. Pidge uses her brilliance with teach to help out not only on the Castle on Lions, but with the Lions themselves. Including outfitting her Lion with a cloaking device.
Though the youngest of the team, she is a valued member, and has saved the team many times over.