obsessive
adjective
°Prone to cause obsession.
"''The idea is too tempting, it's obsessive"
°Having one thought or pursuing one activity to the absolute or nearly absolute exclusion of all others.
"''Hard-core fan's obsessive behavior may take over their lives"
noun
°A person who is obsessed, who has an obsession.
synonyms: unrelenting, unyielding, headstrong