The major points have already been addressed and dissected, so I’ll add one thing:
Talking little doesn’t mean saying little.
This is one of the more difficult elements of playing a reserved character and where many people fail. People who have been shaped through tragedy aren’t selectively mute. What many do do is be wary of strangers. They’re reluctant to give away information about themselves because it might leave them vulnerable. A stranger inquiring about them is suspicious—‘why are they asking me this, what do they want?’
But even these people have friends, often very good friends; people they’re comfortable enough around to laugh and talk. People they have warmed up to. This is a necessary element. Without it, your character has no depth, and worse, no reason for people to want to interact with them.
source: suffering builds character