It has been said that people enter our lives for a reason, a season or a lifetime.
Reason (a project or one-time activity, a “guardian angel” encounter when someone steps in and moves you out of a dangerous situation, a fleeting/swoop by lesson)
Season (a short term; perhaps a few months or years, an interaction that teaches you lessons that you may not have learned otherwise.)
Lifetime (long term connections that may begin at birth or anywhere along the timeline, that endures, perhaps despite challenges, or may even strengthen thus)