Behind the woeful visage of a sad, tired old man, there lies a plethora of mysteries.
Quenzin first enters the story as the sole occupant of a crashed shuttle he wasn't supposed to be aboard, and he doesn't know why he was brought there, where the rest of the crew is, or why they left him to die alone.
To make matters stranger, when Chielle Havello Sai dragged him from the flaming wreckage, he was covered in blood and clearly in distress, yet showed no visible injuries.
And while he alludes to the existence of a sister he loves and children he may or may not have, most of his backstory - ESPECIALLY the details about his estranged family - is off limits to anyone he doesn't trust.
If the style of his clothing looks similar to Chielle's, that's because it is. Between the shuttle crash and the brutal events that preceded it, his former outfit was tattered beyond repair, so she loaned him the biggest coat and pants she had - and they were still noticeably too small for his 6'5" frame.
You can see the height difference between them in the image below. Unsurprisingly, there were no shoes in the facility that fit the towering rescuee, so he'll have to do without for a while.