User blog comment:That Engineer/A reason why Luna and Lincoln would be close/@comment-31022739-20170707044320/@comment-31563773-20170707045706

If you're looking for canon examples, good luck finding them because it's not outright stated. Luna was having issues with how she didn't seem to have a passion, but it seemed Luan and Lynn probably found theirs before she did. So this would cause Luna to have some self-doubt.

Lincoln shared similar feelings in Making the Case. Of course he didn't exactly SAY it (do you seriously need word for word evidence?), but you can clearly see what he's implying since he hasn't won anything. And given how the plot went, Lincoln was willing to forgo the potential consequences as long as he got a trophy.