It was all fun and games until someone had to remind you of your own irrelevancy in the timeline. The timing probably couldn't have been worse, since Len was still sort of recovering from Barry dropping the 'l' word in a painfully sincere way. It wasn't that he didn't believe him. Barry was always painfully earnest and honest. Something that Len had warned him about, though it was probably a good thing he'd ignored those kinds of warnings. All the same, Len wasn't exactly in the business of falling in love. Love in general. It tended to escape him. Primarily because he'd had it instilled in him from a very young age that feeling too strongly about anyone was weakness. He hadn't let it stop him from caring or his sister but he'd still let his heart harden otherwise.
Except he'd been doing a piss poor job of it lately. The more he seemed to try not to care, he felt inclined to do exactly the opposite. Especially where Barry was concerned. And he'd almost fallen into the illusion that this was something he could have. But enter Rip Hunter. With a straight shot of reality straight to the gut.
Len kept all of those fast moving thoughts to himself but visually it was clear he was closing up. Years of practice and a self preservation instinct made him want to curl in, avoid feeling the kind of hurt he'd tried to warn his younger self about not so long ago. His eyes narrowed and any trace of the levity from earlier was gone.
"I'm expendable? Is that the word you were looking for? Seems like that more and more every day following your lead, Captain. Going to find some dark corner in time and space to leave me in if I keep trying to screw this up?" If this tone sounded icy, then mission accomplished.