operate, occupy, take, retain, pursue, enlist, wage, prosecute, affiance, hire, more...

disengage, detach, release, withdraw, disconnect

direct, indirect, active, passive, positive, negative, more...

primary, secondary, firm, most, separate, why

start fighting,   attract or interest,   occupy oneself with,   take interest,   become involved,   get into it,   get involved with,   enter into,   to interest,   to interact with