Supernatural season 15 has set up an almighty final villain for the series in Chuck Shurley, known to his friends as God, but the antagonist shares some parallels with previous villain, Metatron. In a shocking revelation, God was revealed to be the architect of Sam and Dean's misfortune and all of the hardship they had endured since becoming hunters. The deity then turned on the brothers entirely, threatening to end all life in this universe and create another one to play with instead.
Since he's already at the top of the food chain, God doesn't have a typical bad guy motivation. Chuck isn't seeking power or vengeance and he's certainly not serving a higher being. Instead, God's true aim is to tell a good story for his own entertainment. Having previously posed as a novel writer while pretending to be a human on Earth, God has developed a passion for a good, dramatic tale, and this is his reason for tormenting the Winchesters, and the impetus behind his decision to end the world - the story just isn't fun any more. As season 15 has progressed, God has penned a new story for Sam and Dean to play out - one that will act as their concluding chapter.
Although their means might be somewhat different, this motivation is remarkably similar to that of Metatron. Unlike God, Metatron is driven by a desire to get revenge on the angels who cast him out and a lust for power after previously serving as God's scribe. These grievances convince Metatron to empty heaven of its angelic host and claim the throne for himself, attaining a God-like power in the process and becoming the arch-villain of Supernatural season 9. Once his aims are achieved, however, Metatron acts in a similar way to God in season 15. The angel constructs scenarios (as seen in "Meta Fiction") whereby he is cast as a hero against the despicable Winchesters and Castiel. Indulging a love for human stories read while on Earth, Metatron even allows himself to be captured in the name of creating a good "story." Metatron could've killed Sam and Dean on several occasions, but doesn't, because they have a role to play in the fiction he is creating. While in charge of Heaven, Metatron can be found feverishly pounding his typewriter, trying to complete his masterwork.
This is incredibly similar to what Supernatural fans are seeing from God in season 15. Chuck handed over the Equalizer - a gun capable of harming himself - just because he wanted to raise the stakes and force the Winchesters to kill Jack. The Lord has had plenty of opportunities to simply do away with the pesky brothers, but he's coming up with his own theatrical designs to craft a better story - the same reasoning Metatron used in season 9. Also akin to Metatron, God's love of stories was nurtured during time spent on Earth, and both villains share a desire to create an undisputed literary masterpiece. Perhaps the only real difference between Metatron's scheme and God's is that the former yearned to be part of the action himself, whereas Chuck is happy to simply sit back and watch the fireworks he created, but both characters are going about their evil machinations in the same story-driven manner.
Fortunately, these similarities aren't necessarily indicative of Supernatural lazily recycling the same villain template - there is an in-narrative explanation why God and Metatron might have similar personalities. In Supernatural season 8, Metatron is introduced as an angel with a direct line to God, someone that communicated with and was trusted by the creator of all things shortly before he went AWOL. Metatron functioned as God's scribe, taking down his teachings and preserving them in stone. Later, God and Metatron meet once again, and the angel is asked to read over his father's latest work. He makes clear that he isn't a fan. Metatron claims God plucked him from angelic obscurity to be his personal scribe, and this is likely because they are kindred spirits sharing a love of stories and drama.
It's also fascinating that, while God and Metatron both adored their literature, they have very different ideas of what constituted a good story, and Supernatural presents Metatron as the more competent author of the two. By this logic, if Supernatural season 9 showed what would happen when an egomaniac writer is given God-like abilities, season 15 is ramping up the stakes, depicting a storyteller with questionable talents and actual God powers unleashing his will upon the world.
Supernatural season 15 continues with "Our Father, Who Aren't In Heaven" December 12th on The CW.