In the second season of The Mandalorian, Din Djarin took a personal journey that took him well beyond the restrictive rules of his Mandalorian sect, the Children of the Watch. After he was freed of this burden, why would he go back to the same sect?
In the latest episode, Din Djarin leaves Bo-Katan & The Nite Owls to go back to his original Mandalorian sect. The move seems to have eroded any personal improvements he had made before.
Nevertheless, a closer look reveals that this decision is vital to Din's character development and critical to the entire plot of The Book of Boba Fett. Bo-Katan is only mentioned in passing, and it's not apparent how much time has passed since the end of the previous season.
There is also no explanation about the nature of Din's departure. What seems strange is that he would be back to the sect after everything he has learned of the fanatic group.
Still, there are subtle hints regarding his motivations for doing this.
Din spends more time with Armorer and Paz Viszla, the last two remaining members of the sect. Nevertheless, his new companions help demonstrate why he switched sides.
Boba Fett makes no appearance in episode 5. Although that comes off as strange at first, it later becomes apparent that his absence helps Din align his ideals with Boba's before the latter can be of any help.
So far, Boba has been finding out how important family can be as he tries to establish his own clan. In contrast, Din is away from Grogu, his only chosen family member.

Consequently, his decision to go back to his original Mandalorian sect demonstrates his search for something that can fill the void Grogu left after he was separated from him. Still, even though he is back with the Mandalorians, it is clear that he is very distracted, especially when using the Darksaber.
He also has the Armorer make a gift for Grogu, which shows where his priorities lie.
When Din abandons his sect, he has no family, although he understands he needs one. For this reason, he has to go back to his old sect, as being around them makes more sense given who he has become and what he desires.
On three occasions, he takes off his helmet. Two of these times were done to protect Grogu. The third time he takes off the helmet, he also does it for Grogu, but to show his love.
Without a doubt, rejecting the ways of his old sect and forging his own path is a bit of a struggle for Din, although it has given him a chance to focus on his clan. This change acts as a setup for the rest of The Book of Boba Fett.
Din's focus is on making a future for his family, and it appears that his story and Boba's are a perfect match. Both are working towards establishing their clans.
There are just two episodes remaining, but there is still no information on how The Book of Boba Fett will eventually end. From the look of things, Din and Fett will have a mutually-beneficial relationship since their story arcs seem aligned.
Best of all, the fifth episode has at least explained why Din Djarin had to go back to his original Mandalorian sect, even though it makes no sense at this point in his story.