Xenia is all about the relationship between the host and guest. Both parties are expected to be well-behaved and generous in their interaction. There was also an expectation that such kindeness should be returned if the opposite situation were ever to arrive. The concept was also inter-generational, with family lines maintaining a mutual bond created through reciprocal hospitality of each other. In book 6 of the Iliad we see Diomedes and Glacaus have an interaction which makes them realise their family has a history of xenia going back multiple generations which instantly prompts a bond and an exhange of armour in a symbloic gesture of mutual trust and comradery.
These obligations seemed to be very important to the culture at the time. So much so that it was considered the domain of Zeus (Zeus Xenios) to protect strangers seeking shelter. There are plenty of examples in myth of people breaking the sanctity of xenia and receiving divine punishment for it.
Another interesting fact is the difference in quality of the armours exchanged. One was incredibly valuable (gold or bronze if I’m not mistaken) and the other one was relatively poor.
Xenia was such a powerful social norm that for a warrior, in the heat of battle, is perfectly fine to temporarily be nude, exchange your finest armour for a lower grade one, and still be happy about it.
Oops I was mistaken; The article I linked is just a review of the book (and another book). It was Emily Watson's Introduction to her transation of The Odyssey that I was thinking about that touched heavily on xenia. You will be able to read it in the kindle sample https://www.amazon.com/Odyssey-Homer-ebook/dp/B06XKNHGN1/ .
