Spiritual

Companionship is based upon Affection, intrinsic Qualities of Empathy and Bonding. All animals, birds fowl , fish, squirrel care for their young with Affection: indication that they are Empathetic. Dogs , Hens manifest deep Companionship ( loyalty, concern, understanding, affableness, friendship): Intrinsic Qualities. Some humans are Empathetic.

When a being passes away, the Emotions Thoughts in her "spirit energy" is yet existing; Since it's 'spirit energy' that enlivens a physical body ( keeps it alive and gives it the ions& photons etc. manifestation), the Desire (& intensity) for Immortality Love ( Affable)  in the 'spirit energy' is able to influence the physicality  accordingly ( towards Immortality).  A beyond 'time, space, matter ' characteristic, Immortality is possible in immediate, in future and in same Locale or another.

A being can continue to love respect someone who has passed away and have the same level of affection for him/her as when he/she was alive : Love is stronger than 'death' , a Truth. This "truth" also affirms that Love ( affection, friendship) is not subject to 'death' , but is a Stronger spirit energy than 'death' is.

In relationships , Teaming has a different effect upon one's Atoms, molecules and excitement than does enmity: Physiology is affected by one's thinking and Spiritual choices at deeper level.   Immortality of physiology is possible through Unity oneness with Immortal loving truth essence ( already prevalent in all Sentience spirit energy). Some scientific groups have been propounding the Reality of Immortality ( favorable eternal Loving existence) of spirit, soul and body.

Immortality is from Volition Choice of each being , is personally unique to each being , is a Spirit ( Spirit being 'energy',  is indestructible) Soul quality and not based upon anything that is external or progeny . Immortality in true sense is Truth whole, a Favorable existence, friendship values, loving , healthy , ageless and cognitively exciting.

To be in Semblance / alikeness/ similarly/ image / inner Similarly/ similitude / sameness in Intent , thoughts, conscience, inner Atmos, emotions and manifest affection: Companions , irrespective of external differences , think and feel alike . Affection is the factor that enables Companionship. Companionship is eternal : the circuits that are responsible for intrinsic bondings are of eternal indestructible spirit soul energy Realm