Baba Metzia 98b - Shliach of the Borrower

The mishna says that if the lender sends his animal in the hands of his messenger or son, if the borrower didn't tell him to send it in the hands of that person, the borrower isn't responsible until he actually receives it. But if the borrower told the lender to send it in the hands of the lender's son or messenger, as soon as it leaves the reshus of the lender, the borrower assumes full responsibility for it. Clearly, the mishna considers even the "shliach" of the lender, who the borrower never even spoke to, to be a shliach of the borrower so that the borrower assumes responsibility as soon as it leaves the jurisdiction of the lender. Through what mechanism does this "shliach" of the lender, turn into the shliach of the borrower? The Ritva suggests 2 possibilities: 1. Although normally that concept of זכין לאדם שלא בפניו only applies to a zechus, not a chov. Here, where the borrower says to send it, he is agreeing to assume responsibility immediately. Therefore, we would say חבין לאדם שלא בפניו מדעתו - meaning that with the consent of the individual we can allow zechiya even for something which is a chov. 2. It is working using a similar concept as "omer imru" (6th perek of gittin - the ritva himself doesn't make the connection but this is how i understand what he means). Reuven can tell Shimon to tell Levi to serve as Reuven's agent, therefore the borrower tells the lender to have the "shliach" serve as the shliach of the borrower.

The gemara discusses how the non-jewish eved of the lender can serve as the shliach of the borrower. Tosafos raises a question based on the gemara 96a that a slave can fill his master's shoes to consider it a case of שאלה בבעלים, so when the lender sends his eved we should exempt the sho'el due to שאלה בבעלים. Tosafos (and Ritva) explain that the case on 96a where the gemara discusses whether a shliach of the lender and the slave of the lender qualify as שאלה בבעלים, is only when the initial agreement is that the lender himself should work for the borrower, but decides to send his agent or eved in his place. But, if the initial agreement between the borrower and sender is to send the animal in the hand of the eved, it is not שאלה בבעלים, rather it is like borrowing 2 cows (cow + eved). The Ritva is bothered according to the second approach, under what circumstances would we consider the eved to be working for the sender and therefore creating a case of שאלה בבעלים to exempt the borrower, and when do we consider him a shliach of the borrower? The Ritva says that if the lender forces his eved to go, against the will of the eved, he is clearly working for the owner (who is accepting an obligation to work for the borrower) thereby creating a case of שאלה בבעלים. The eved can't be working for the borrower against his will, because the borrower doesn't have the power to force the eved of the lender to work. But, if the eved is given a choice, and on his own agrees to the masters request (when the master says that the borrower asked me to ask you to bring him the cow), the eved becomes an agent of the borrower to make the borrower responsible immediately and it is not שאלה בבעלים.