These characters have something in common in their narratives. Both Holden and Jake spend time "on the run" for several days, dealing with harsh conditions.
Also, both of these characters seek an ideal escape from the life and the trouble they are experiencing.
As a bit of trivia, a lake fits into both stories.
The first thing that I thought of is that they are both outsiders. I never really thought to compare them before. Both have dismal stories. They have bad luck, never fit in anywhere and have a difficult time making sense of their world. Both also have feelings of invincibility or ambivalence as they do not like what they see in the world.
I would want to focus on the way in which both of these characters show they are positioned outside of the respectable boundaries of society. They do not fit in and part of their conflict and struggle is the way in which they react to this sense of being outsiders. In their journeys to gain some measure of love and acceptance they offer commentary of the societies of which they do not feel included.
Comparing these two characters might seem difficult, but they really do share some significant similarities. First, Frederic and Holden are both caught up in difficult worlds not of their making and in which they do not belong. In their own ways, both are outsiders, but they struggle to function in their circumstances before finally leaving. Each of them then sets out on his own, making a journey.
Both Holden and Frederic experience a sense of isolation and loneliness, and both of them seek love and human connection to relieve those feelings. Frederic's relationship with Catherine and Holden's love for Phoebe are reflections of their emotional needs. Holden and Frederic are both deeply sensitive. Each has been touched by death, and both of them feel deep grief.