to join or to make oneself one with something through friendship
Alonso de Molina:
cetia ti. (pret. oticetixque.) vnirse, o hazerse vna cosa por via de amistad. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 18v. col. 1. Thanks to Joe Campbell for providing the transcription.