The clone troopers of the 501st Legion are a tight-knit bunch, loyal to the end to their Jedi General, Anakin Skywalker. Jesse was a hard-fighting patriot who proudly wore the cog-shaped symbol of the Galactic Republic on his helmet, and as a large tattoo that covered his face.
When Rex was injured in the line of duty while tracking a fugitive General Grievous on Saleucami, Jesse was deeply concerned for his well-being. Jesse assumed command of the 501st unit stationed with Rex, while his ailing officer recovered in a local farmhouse.
Jesse was in the same squad as Kix, the unit medic, while hunting down General Grievous on Saleucami and serving under General Pong Krell on Umbara.
Jesse can appreciate Hardcase's hunger for action, which translates to explosive firepower on the battlefield.
Though Jesse never met Cut Lawquane, he did spend some time on Lawquane's farm on Saleucami, ensuring that it was a safe haven for Rex to recuperate in. Jesse was cordial to Cut's wife, Suu.
Jesse served under General Pong Krell when the Besalisk Jedi Master was given temporary command over the 501st legion on Umbara.