A minor character who is given a greatly expanded role in the later part of the series, a new adaptation of a story, or in the Expanded Universe. This often arises simply due to the creators realizing that said character holds far more story potential than they originally thought, or at the very least, re-purposing this character for a greater role in the narrative is better than making an entirely new character.
A male character who is so good-looking and unintentionally charming that he becomes a babe and stud magnet, (the studs being either bisexual or straight). Some of the other characters may question his sexuality and he'll keep them guessing, which results in Ho Yay... unless, of course, he is the love interest.
These characters need a hug. Badly. But don't expect them to ask for one. A subtrope of The Stoic, unlike other woobie characters, they won't cry, angst, or outwardly show how much they're suffering at all. (Internally is another story). They don't want your pity, and in a great number of cases, will deny having emotions at all. Don't be fooled. The plot has heaped complication after complication on them, and silently, internally, they're suffering.