was reed's death particularly tragic/unexpected? or was it more just age-related? not that losing him at all wasn't a tragedy.
ReedWalk survived that illness that swept through the house but was sick from then on and died a few years later from complications related to that and the poverty they had all been living in before and especially after.
PenWell was sometimes angry with Reed for being another he had to care for on top of being the only one working, and seeing his previously very brash partner gently and quietly reassuring him when he came home just made him angrier at life in general because it was so out of character (Reed was kind to him don't get me wrong but he was a hug-wrestle "want me to kill him for you?" kind of person - after the illness he stopped having the energy to have his personality on at full volume and the difference was stark)
Pen is still deeply bothered by how uncharitable he was in his thoughts at the time, even though he didn't lash out in any particularly awful way. He views the way he was unable to fully conceal how upset he was (how he couldn't control his venom production) as a form of lashing out that he's embarrassed by - he often views the venom he was making at the time as an expression of anger but most who saw him around that time would have described him more accurately. He was terrified. Constantly.
Trying to talk about Reed brings up all these feelings of regret and survivor's guilt and inadequacy much much more strongly than anyone else he's lost - and worse, the thing he feels he "learned" from all that was the importance of not letting his emotions hurt those around him. So he just doesn't talk about Reed.