How bad is the character grind? Before DNA released, people were worried that characters, being free, would take an unreasonable amount of time to farm. It turns out that once you have their Secret Letters, it takes ~1 hour give or take to farm a single copy depending on your efficiency. You can farm for their dupes in the same way. The second worry was weekly bosses gatekeeping Secret Letters. If you focus on farming one character's Secret Letters, you'll have a very decent chance of getting them that same week depending on your luck. But failing that, you'll get them the following week. I was able to obtain Hellfire on week 1. Eventually, Secret Letters locked behind weekly bosses will be moved to the Covert Commissions shop and will be purchasable with Secret Letter Clues. The third worry was that Secret Letter Clues -- used to purchase Secret Letters for characters, weapons, and Demon Wedges (equipment) -- would eventually run dry and become a huge bottleneck. Thanks to a post-launch update, they drop pretty regularly from Commissions now. So far, in my opinion, the character grind feels extremely reasonable and rewarding.