Contracts

We all understand how a contact works in black butler but what if demons are not the only ones that can contract?

I know I have been doing a lot on grim reapers, but what if they can make a contact?
For example, a human wants revenge on something ( * cough cough * ciel ) and instead of having a demon they have a reaper, of course the reaper can't do everything a demon can but they are more human the demon and I think I would prefer a reaper to a demon.

The contract works like this
Once you state the reason for the contract with ( following reaper), they will take your soul without issues once your requests have been met, they will extend your cinematic record to meet the criteria to complete your requests, if you die before you have accomplished the request, the reaper will be infected with thorns of death, if the thorns of death are already present, the reaper will die. If all requests are met and the reaper has thorns of death, they are cured.

A reaper may not help you kill another living being, only if your soul is in present danger,the reaper may kill, even so the reaper must then collect the fallen soul and face the error of what they have done.

Something like that, I this hard to do because a reaper must still be a reaper and help you, I don't see many reapers knowing much about this, and if they did its life or death to them, but if a reaper had tod( thorns of death) they have nothing to lose so why not?

I see reapers being limited
they can't sense when your souls in danger 
There glasses would be a issue if broken or lost
They could be far away and it would take time for them to get to you

But they may have advantages too
They look normal, not counting the eyes, they blend well
The scythes are unbreakable, so that one weapon will spell life or death
You can work out a word to inform them and tell them your in danger
There contract would be more powerful depending on how powerful your soul if or your will to cling to life,

And I think they would have different ways that a demon may or may not have

When you say whatever code word, they can hear it and will get to you as quickly as possible,
Your soul would be protected by a reaper against demons,
If you have pets I don't doubt that the reaper would claim then as there own after your death, so pets would be in good hands
Reapers have a wide range of personality
Grell, undertaker, William, who knows what the reaper will act like!

This is a work in progress headcannon so expect more