<p>Most humans just die because they cannot handle it. Otherwise, just look at Dark Sakura. </p>

<p>There was also Kirei who was revived by the mud, who was then immune to True Assassin's Delusional Heartbeat. </p><p>ANd Kiritsugu who was slowly dying from his contact with the Grail Mud. Basically, the result varies from person to person. </p>

<p>In Kotomine's case, it was just a side-effect of Gil not being able to be blackened, so it's not not exactly the same as falling into the mud. Kiritsugu's case was a curse that Iri Avenger put on him rather than the effects of blackening. Normally, people will just melt like Shirou in a number of the bad endings. If they don't, then they should end up twisted like Sakura. </p>

<p>Sakura also just turned out that way because she was a Lesser Grail, who then fused with Avenger. I think blackening only occurs with spirits, so humans just die. </p>

<div class="quote">Sandubadear wrote:
Sakura also just turned out that way because she was a Lesser Grail, who then fused with Avenger. I think blackening only occurs with spirits, so humans just die.</div> <p>Just a memo but... sakura had a piece of the last lesser grial irisviel which was fused with angra manyu... she WASN'T the lesser grial, she just was able tu function like one because she had that piece </p>