WARNING: The following contains spoilers for Daredevil #26 by Chip Zdarsky, Marco Checchetto, Mike Hawthorne, Adriano Di Benedetto & VC's Clayton Cowles, on sale now.
Even though battles from the King in Black battles taking place throughout the Marvel Universe, it seemed the people behind bars might be safe. However, that turned out not to be true, and Daredevil ended up in the middle of the battle with Knull's forces, all while serving his time.
Since he accidentally killed a street criminal, Daredevil has been falling apart, and his actions finally landed him behind bars. since he started his time in prison. He fought crime on the streets for his entire life, but while in prison, he hears what everyone is saying and listening to heartbeats to realize there is nothing but sadness, confessions, loneliness, and regret. It has made him see these men differently. Then, Knull attacked the prison, and Daredevil's thoughts made him a prime candidate to bond with the dark god.
The symbiote god got into the prison and began to take over prisoners and guards alike. They had no chance, even after Daredevil begged to be let out of his cell to help in the battle. He quickly realized that he is still called into a fight to protect those who had lost their way, even when he is in prison. But even with Daredevil fighting to protect them, it wasn't enough. Matt Murdock is only human, and he was not strong enough to shake off a direct personal assault by the dark god Knull.
Throughout King in Black, superheroes like Captain America and Cyclops ended up trapped inside the symbiote and soon became symbiote soldiers fighting against their own world. However, things in Daredevil were shown a little differently. Knull spoke directly to Matt Murdock, and he essentially convinced him to bond with him. As Knull put it, he was a being of pure power, and Daredevil is famously the Man Without Fear, which means that they are unstoppable when combined.
Knull's other enslaved heroes have already torn through New York as Knull's Knullified soldiers. However, it seems Daredevil is more than that. If Knull personally bonded with Daredevil, that could make him the dark god's human avatar. It also makes the Man Without Fear the ultimate weapon in Knull's war with the people of Earth. This is the kind of thing that Daredevil fans have seen before in the Shadowland event, where Daredevil gave himself over to demonic possession.
Now that Knull has bonded with Daredevil, he poses a serious threat to the remaining heroes defending Earth. Unlike others, Daredevil has senses and can hear when people are lying, knows where people are hiding and could find anyone who might be a threat almost effortlessly. With the abilities of Knull and his thirst for power, Daredevil could be the one man who could finally bring down those who oppose the symbiote god.
For the last year, Matt Murdoch has been beating himself up and forced himself to go to jail for crimes he placed on his own shoulders. Now, Daredevil has found a being who promises him a chance to be better and has, at least for now, given himself over to evil once again.