|Agent Leo Fitz|
Leopold "Leo" Fitz is a Scottish-born S.H.I.E.L.D. agent and scientist. A genius engineer, he is one of the youngest and most prominent members of S.H.I.E.L.D.'s Sci-Tech division, and inseparable from his research partner and best friend, Jemma Simmons. He, along with Simmons, was recruited to Coulson's Team by Melinda May and worked with them on all of their missions. While on the team, Fitz became good friends with teammates Grant Ward and Skye.
During the HYDRA Uprising, he became jealous of Simmons' friendship with Agent Antoine Triplett. Fitz was an active participant in hunting for John Garrett and the rest of the Centipede Project. He was shocked by the revelation that Ward had been a member of HYDRA all along, and refused to believe it, resulting in several arguments with Simmons and the rest of the team. Fitz was captured by HYDRA along with Simmons, and met Ward again.
When Ward was ordered to kill them, Fitz fruitlessly begged Ward to have mercy, and was dumped into the ocean in the Bus' Medical Pod with Simmons. They survived the fall, but were trapped on the ocean floor. Fitz devised a plan using the pod's oxygen bottles to get them out of the pod and to safety, but there was only enough oxygen for one, and while confessing romantic feelings for Simmons, he saved her. However, this resulted in him spending a long period of time without oxygen, causing brain damage.
As time progressed, Fitz's condition seemed to get better with help and support from his fellow S.H.I.E.L.D. colleagues. Slowly regaining his skills, Fitz was able to get back into doing active field and lab work, and played an important role in the conflicts with Robert Gonzales' S.H.I.E.L.D. faction and during the War against the Inhumans.