I feel like people don’t often talk about Kylo’s line about the ‘lightsaber belonging to him’ despite how big of an insight it is to the past and what we could possibly learn about in the future films.
That lightsaber was passed down to Kylo when he was training (EDIT: there is no confirmation that he received the lightsaber while under Luke’s guidance) and it somehow ended up in Maz Kanata’s possession. We don’t know what kind of relationship Kylo and Maz might have shared, but she seems insightful about the saber’s history and how the Force works and she also highly encourages Rey to take it. Maz has said that she sees the same eyes in different people. She tells Rey that whoever she’s waiting for to come back and take her home is never going to come– touching on Rey’s deep loneliness and abandonment issues from being alone for so many years. She then proceeds to tell Rey that the belonging she seeks isn’t behind her, but ahead, and tells Rey to take the lightsaber which was last in possession of Kylo.
I also think it’s important that Kylo was the previous owner of the saber before Rey touched it and was sent into a flurry of intense Force visions. Yes I think the Force itself had a big role to play in guiding Rey to the saber and showing her those visions, but we have heard multiple times about Kylo and Rey’s mysterious connection, and the fact that the majority of the things she saw revolved around Kylo plays even more into that.
It’s been said a thousands times by different people over the past two tears, but I really can’t get over how greater forces are at play and drawing these two completely opposite, yet parallel, people together for a quest so much bigger than themselves.