If it seems to you that Ksenia in an informal setting can only be called Ksyusha, you are mistaken. Each Russian name has a great variety of forms and variants, and the name Ksenia is no exception.
In the Russian language, it is customary to form affectionate diminutive names from the "full", the official name that appears in the documents. There are several quite traditional ways of forming such names, but the result is a rather large and varied list from which parents, relatives and people around them can choose a “home” unofficial name for the baby to their liking.
Variants of the name Ksenia, formed in traditional ways
You can go the easiest way: to form names, taking the part of the name "Xen-" as a basis and adding traditional diminutive suffixes to it. The following may turn out: Ksenichka, Ksenechka, Ksenochka, Ksenchik, Ksenya, Ksenya (as an option - Ksesha), Ksenyok, Ksenka.
The first and most common affectionate name that Ksenia is commonly called, of course, Ksyusha. This name can be made more tender by adding a suffix to it: Ksyushenka. But from the part of the name "Ksyu-" you can also form a lot of interesting options: Ksyunya, Ksyura, Ksyuta, Ksyunechka, Ksyutochka, Ksyura, Ksyurochka, Ksyuksya or simply Ksyu. And you can also Ksyunya-Kisyunya, if you like.
From the form "Ksyu" you can also "drop" the initial letter and get interesting options starting with "Syu-": Syuta, Syunya, Syunechka, Syutushka, Syutochka, Syushenka, Syushechka.
And you can also take the "Ks-" part as a basis, adding to it all kinds of word-building and form-building elements: Ksana, Ksanochka.
The root "San" is formed from the last variant, and it can also be used to form new affectionate names: Sana, Sanya, Sanechka, Sanya, Sanushka, Sanka, Sanochka.
You can drop the first letter of the name and form new affectionate names from the "Sen-" part of the name. The result is not very common, but also valid options: Senya, Senyushka, Senechka, Senyura, Senyurusha, Senyushka, Senechka and even SenIchka (or even Titmouse)!
Variants of the name Ksenia, formed from the "folk forms of the name
It will not be superfluous to remember that two "folk" forms were formed on behalf of Ksenia: Oksana (Ukrainian version) and Aksinya (Russian version). This means that we can safely call Xenia both by these names themselves and by their variants.
So, on behalf of Oksana, we form the forms Oksanochka, Oksanushka, Oksanka, Oskanchik, Oksa, etc. And on behalf of Aksinya, we can "produce" such pet names as Aksinyushka, Aksyuta, Aksyona, Aksyunya, Aksya, Aksyusha and even Asya.
Show your imagination
Those who like to call their children in a “foreign” manner can also find variants that sound pleasant to their ears and that can, albeit with a stretch, be considered a variant of the name Ksenia. So, you can call Xenia Oxy or Roxy.
Some lovers of original and slightly humorous names can call Ksenia Ksyushentia, Ksyukentsia, Ksyuks, etc. Perhaps such names will not seem too affectionate to some, but one cannot but agree with the fact that they sound fun and fervent.
Of course, this is not a complete list of petting options for the name Ksenia. If you wish, you can show your imagination and come up with something of your own, completely original.