Is an accidental killer allowed to present himself before the blood avenger so that the latter will kill him? On the one hand, he is bringing about his own death, like someone who ties himself up in front of a lion, which presumably is forbidden as taking one's own life. On the other hand, here the killing is permitted, and it is not comparable to a lion, which was given no permission to do anything. If it is forbidden to present himself before the killer, then indeed if the blood avenger kills himself, perhaps it is permitted in his "hat" as blood avenger, but in his "hat" as accidental killer he is forbidden to present himself for death. What do you think?

"Present himself before the killer" is a typo; it should say: present himself before the avenger.

It seems to me, by reasoning, that he is allowed to present himself. Of course he is not obligated, since as a matter of Jewish law his killing is not a commandment. This is taking one's own life indirectly, which is not really a full-fledged prohibition, and here, since it is being done permissibly, it seems to me that it is allowed.

Maybe it depends on the reason an accidental killer is forbidden to leave the city of refuge (even if all Israel needs his salvation). It may be an independent prohibition, and it may be forbidden because by doing so he presents himself before the blood avenger and it is like taking his own life. And perhaps one can resolve that it is an independent prohibition, since even if all Israel needs his salvation he is forbidden to leave, whereas if the issue were simply that it is like taking his own life, then plainly a person is allowed to give up his life in order to save all Israel (if Roi Klein could stop an atomic bomb threatening all Israel). So it must be an independent prohibition (that seems to follow from your words). But it may still be that there is also a prohibition against presenting oneself for death.

Could you sharpen the reasoning for distinguishing between killing with permission (where by logic he is allowed to present himself) and being killed by a lion (where it seems obvious that he is forbidden to present himself, even though that too is indirect causation)?

When the one threatening him is a lion, then he himself has protected status. But when a person who is subject to the law is permitted to kill him, then he himself no longer has protected status. Therefore, if he presents himself, he is somewhat like a dead man walking.

So why would it not be allowed for the accidental killer to present himself before a lion instead of before the avenger?

Because he lacks protected status only with respect to the avenger. For anyone else, it is forbidden to kill him.

Thank you.

A side question: if in the ordinary case of a blood avenger it is forbidden for the accidental killer to present himself, does it follow from that that it is forbidden for the father-avenger to kill himself (because permitted + forbidden = forbidden)? Prima facie that seems so, but maybe such a permission overrides any prohibition along the way that essentially blocks the permission.

I'm not sure that when a person kills himself this is called presenting himself for killing. Simply speaking, he is always already present and available to himself, and there is no act here of presenting himself. The decision to carry it out belongs only to the killer (that is, to him as killer), not to the victim (to him as victim).

Okay, that is a different line of reasoning. But let us assume for the sake of argument that this really is a problem of taking one's own life. I am asking about the rules of override (that is why it is a side question): is it possible that a permission to violate "Do not murder" (as a blood avenger) would here be essentially blocked because of a side prohibition (taking one's own life) that always appears in this person? The side that says it would be blocked is simple: the permission of blood-avenging removes only murder, and just as presumably it is forbidden for the avenger to avenge on the Sabbath, because who permitted him to desecrate the Sabbath. The side that says it would not be blocked, and that he may kill himself, is that a permission to kill permits killing in whatever way, and just as it overcomes "Do not murder," it permits any other prohibition unless that other prohibition only arose incidentally. This is based on your distinctions in several places between different kinds of overrides.

By the way, I will note that in column 366, regarding the law of one who rounds his own hair and is lashed also because he lets his hair be rounded, you concluded that the rule that he gets 80 lashes is not self-evident (like all the other cases where the cutter and the one being cut who assists both get lashes), because here there is only an "act of rounding" and not an "act of being rounded," unlike the other assisted cases. [Except that in the one who does the rounding, this is a special law of liability and it splits into the cutter and the one cut. Therefore Rabbi Joseph Engel sees a novelty in the 80.] And here too you said that one who kills himself is not like one who presents himself (just as one who rounds his own hair is not like one who assists in being rounded). It seems to me, Rabbi, that for you the reasoning is one and the same, although I have not yet thought it through properly.

I don't know.
As for presenting oneself, the reasoning is simpler, because by definition he is already present and available to himself. In the case of the one being rounded, that is a line of reasoning, but it does not follow from the definition itself.