Warning! Spoilers ahead for The Rise of Kylo Ren #4
Star Wars: The Rise of Kylo Ren concludes with its fourth issue with Ben Solo's transformation and corruption to the dark side is complete, regardless of how willing he was to embrace it. Ben Solo has died, and Kylo Ren is born - and is ready to fulfill his role as Supreme Leader Snoke's apprentice in The Force Awakens, before becoming Supreme Leader himself in The Last Jedi. Despite this, Ben would be redeemed and reborn by the end of The Rise of Skywalker, before giving his life to save Rey.
When he became one with the Force and his body disappeared, his mother Leia's body disappeared as well, having felt his passing. As the comic reveals, Leia also felt Ben Solo's first death as well. The Rise of Kylo Ren, from writer Charles Soule and artwork from Will Sliney, features Ben Solo immediately after Luke's moment of weakness, where he feared his nephew's enough to momentarily consider killing him before he could be fully corrupted to the dark side. Unfortunately, this is what ultimately pushed Kylo even further towards the dark, allowing Snoke (and Palpatine) an even greater hold on him.
After the Jedi temple's destruction, Ben retreats and goes to Snoke, who suggests that he take a new name and join the Knights of Ren, who could teach him much about the dark side. However, Jedi survivors pursue Kylo, hoping to bring him back. In The Rise of Kylo Ren #4, this leads to a confrontation between the two Jedi and the Knights of Ren, with Ben in the middle. One of Jedi seems to start bringing Ben back, before Ren kills him. This causes Ben to fight Ren with rage and fury, as the voices of Snoke and Palpatine urging him to kill Ren and give in to the dark side. Ben does, and his descent into the dark as Kylo Ren is felt by many. However, the most tragic reaction comes from his own mother, who feels the loss of her son from across the stars.
Leia feeling the loss of her son and his turn to the dark side is significant, as it essentially creates a poetic symmetry later on down the line at the end of Ben Solo's journey. She first feels his death when he falls to the dark, then feels his death again when he returns to the light. It just encapsulates how much Leia loved her son and hoped longer than most that there was a chance for Ben's redemption. Leia's role and mere presence were instrumental in pulling Ben back to the light despite Kylo's resistance. Eventually, it was her own death that opened the door for Rey to get through to Ben and gave him the opportunity to make things right.
The Rise of Kylo Ren #4 is on comic book store shelves now.