That brother would be me. It doesn't have a negative effect unless the person u have bound urself to intends to do harm to themselves or get themselves damned. You just have to make sure that u know and trust the person well.
There are more negative effects than that. It is not specific enough in the words to allow it to only affect the other person if one does harm to themselves.
Simply because you have not noticed anything else, does not make it any less possible.
Your soul grows and evolves. If tied to someone else, it can hinder that growth. If in the spell you are saying to feel their pain, you cannot garuntee that it will only be a certian kind of pain that comes from a certian action.
Again, I am unsure if you can actually bind your soul to someone else. But that's neither here nor there.
Looking at the words and intentions alone, I offer my input to the possible side affects.
i like the binding spell personally and for some reason, i dont know why, even though i cant relate at all to that desperate situation that you were placed in i feel that you are right.
What you did is definetely reckless and half thought out at the moment but i beleive that your spell worked because of all the feelings you had to that person and so... NO OFFENCE TO ANYONE AGAINST THE SPELL... i have to say that i beleive the spell wont have the negative side effects if your feelings are so strong and good that it binds the souls in a good way.
Although i do have to say that this spell has to be used as a last resort because this isnt a regular spell you can cast at any time to anyone. So i think this spell is very cool and it should be used with discretion.
There are alot of different types of pain.Spiritual,physical,and emotional.Some are alot harder to endure than others.I do think the spell needs to be worded better,but it reminds me of a lost friend that I would have done just as you did for.I would have acted without hesitation to make them better.So I do commend you on your loyalty to this person,just be carefull.
lol. Yeah.. I'm currently working on better binding speels to bind a whole bunch of different psychic connections of souls, emotions (mainly love), pains, and thoughts. It isn't as easy as changing a word in the spell.. althogh the "from mind to blood and blood to mind" is going to stay... it wa my grandfather's beginning spell starter... the spell was, if i remember correctly: "From mind to blood, and blood to mind, let this be true, that you will do no harm, and as it be, from mind to blood, and blood to mind" Or something along the lines of that...