Earth was a fascinating place, from the breadth of human endeavors to the sheer beauty of the planet. All the spoken and written Earth languages stored in his database filtered through Ratchet's processors while he devoted several threads to deciphering a particular passage in a very difficult text, until something triggered a memory recall, pulling Ratchet away from his absorption.
Worry filled his spark, thoughts of his missing comrades pushing aside the translation work for a brief moment. Optics focused in the middle distance, snippets of video interweaving among dialogue stretching back millennia.
One in particular sent a cascade of emotions throughout his systems. Loneliness, friendship, and longing all swirled together into a complex mixture, triggering more personal recollections. A gruff voice, coming from a battle-scarred form, one who had always been there, until he wasn't, leaving him bereft and anchorless. Sometimes he still saw that black form from a corner of an optic, haunting Ratchet with thoughts of what could have been, if there had been no war.