It's important to have a choice by which you can tie a Sovereign to a particular Civlization (the one you previously selected). In new games with that particular Civilization, that Sovereign would appear as one of the availables but not with any other. Why? Because if you tie with to a concrete civilization, that should give you access to specific perks/talents/traits/advantages/disadvantages/flaws/... related to it.
As I said in another thread, the Sovereign grows up in a concrete enviroment. If you don't tie him to a civilization you get the usual things but if you tie him to a civilization, it means that he really feels identified by the people of such (in theory, with those he grew up... I also said something about non-humans being grown up in different societies but that's more moddding department). Such identification would mean a better understanding of that people and to be better recognized by them.
Not a very important point by I think it's interest to at least mention it again.
-----------
More in line with the topic, which is just purely traits for the Sovereign and that in no way tie him to a specific civilization:
There is a book and a game. Both are, obviously, different and in some areas they will be the same while in others it won't be possible (a book doesn't have to care about balance, for example). In the end, players are only going to care (mostly, usually) about the bonuses but the presentation of those different bonuses and why you can choose some but not others is important. In the book the presentation of the character has nothing to do with the bonuses but help us to understand the motivation of the character and why he is who he is and why he does the things he does.
As in the book, the Sovereign has a past behind him to the moment in which the story begins. His access to essence and being inmortal define him as Sovereign but his actions as such are not defined by that but how he was raised, the things he learnt and how as a person he is. A knife in your hand doesn't make you an assasin unless you start killing people with it.
According to the Lore a hundred years has passed since the "end of the world". Was the Sovereign alive then? Was he born after? How is the society he was in?
In a such harsh enviroment and with civilizations reduced to tribes at best, some roles that we could consider possible, might not be so possible. And obviously, what could be possible for a human, might not be possible for a fallen.
In the Supposition World our Sovereign could access some different backgrounds, which "simply" reflect that general type of life that the Sovereign had before he started the whole "Sovereign Business":
- Merchant: altough might not be in the same sense we usually understand it, surely someone had to trade/bart with other tribes to secure those things that they lacked.
- Hunter: People needs to eat and someone must provide. Ranged combat and survival would be his expertises.
- Warrior: Not part of an army as in such times armies could not exists and not that these warriors had good equipment (apart from a stick... possibly pointy). But when dealing with enemy tribes that compete for resources, you surely want someone better prepared that a kid with a stick.
- Bard: Traditions only die if people forget about them. Lorekeeper of the clan/tribe, or maybe just some travelling minstrel and possible womanizer.
- Rogue: Living in the shadows of the society and living off the efforts of those surrounding him.
In those examples, backgrounds are based in possibles roles of the Sovereign during his mundane live (if any). And altough they should have some bonuses/abilities associated with them, their true strength would be in unlocking special traits/skills associated to such backgrounds. If you were a normal merchant without ambitions, with just the Merchant background would be enough. But if you were a good merchant, you surely learnt some tricks that non-merchants could never develop.
- Black Market: it's going to exists even if you don't want. But if you are a Merchant or a Rogue, you can influence it and/or get some benefits from it.
- Battle Hardened: Only for Warrior. Weapons and armours have no secrets for you. You can equip any of them without penalties and get a X% bonus in combat to XXXXXXXX and XXXXXXX that increases each level by X%.
- Acrobatic Combat: Only Rogue. Gain a X% to XXXXXX while in combat, that increases by X% each level. Allows you to "Manuever" while in combat and strike your enemy from a vulnerable spot (aka +XX% to attack when using the "Maneuver").
Just some simple examples. Some of those traits/skills/perks could be common between those backgrounds if it makes sense (Black Market) while others are exclusive. This makes that not all the traits are available to the player and makes you to choose. You could have more than one background (a Warrior that ended as Merchant) but it would mean you would have access to Warrior and Merchant traits but less points to spend in them.
Then we would have those common traits that anyone can buy: Lucky, Friendly, Blood of the Kings/Emperors, Elemental Attunement, Cursed, Brilliant Mind, Paragon, Zealot... Some of those traits at the same time could lock others (Lucky would prevent you from selecting Unlucky). Altough these traits could have effects in the civilization (a charismatic trait that doesn't affect your civilization would be very bad), if it'd be possible to tie the Sovereign to a specific civilization (with a trait), then it could unlock civilization specific traits for the Sovereign to purchase.
As in with traits unlocked by backgrounds, it'd be nice if traits could be: positive, positive with drawbacks and negative. The last one giving some points instead of costing them.
--------------
When talking in a thread about coats of arms, I found very interesting to have dymanic coats of arms that would change according to your actions and provide some bonuses (minor or whatever, just an idea). People were not fond of it (because of cosmetics?) but in the end is as some people asks here of getting bonuses along the game depending of your actions. And I like that idea. If your Sovereign does nothing but trade all the time, he should become a better trader (get bonuses for it or something like that). Maybe they not need to be Sovereign specific and have them as civilization bonuses (the trading would be done by merchants after all, not that the Sovereign is doing all the trade himself). But in things he is directly involved and that he does quite often (even if he fails), he should get some bonuses. Maybe.