Restrained
Part of speech: adjective
Definition: Held back, limited, kept in check or under control.
Part of speech: verb
Definition: To control or keep in check.
Example sentence: Stiles is a version of me that rarely exists in the real world. He's so confident and extroverted, and I'm much more restrained and internal.
Unostentatious
Part of speech: adjective
Definition: Not ostentatious; simple; unpresuming.