The almost penultimate post that expands on the characters & characteristics post fleshes out the first part of the inferences & relationships aspect. Inferences drawn from a character's attributes can reveal more about a character. Proficiency in sword indicates practice in some way; was there a tutor or a hidden gladiatorial past? Religious callings, personality quirks and even preferences in clothing can all reveal backstory which can lend versimilitude.
You don't need to be an improviser with mad skills to work out this stuff. Certain problem solving types tend to work to five 'why' questions about something which usually exhausts all the options and provides an explanation which can be worked with. This can be tied to the ladder of inference devised by Chris Argyris, which can be summarised as below.
1. Observable attribute.
2. Selection of data based on attributes.
3. Assumptions based on inferred meanings.
4. Conclusions based on inferences.
5. Beliefs based on conclusions.
6. Actions taken based on beliefs.
Steps 2 - 5 provide a feedback loop called a reflexive loop where beliefs can shape selection of data and reinforce those beliefs or try to fit the observable into that framework. These can help to flesh out a character by giving them beliefs consistent with their attributes. They don't need to be true beliefs either - how many villains believe they're acting for noble purposes or that they're in the right for doing something?
Inferiae are sacrifices made to deceased heroes by the Romans as tributes. They are the reason that much of the action in Titus Andronicus takes place. What sacrifices has your character made to the past? Do they hold them in reverence or are they post-modern iconoclasts believing nothing but what exists here and now is of value?
Had I realised I was going to take this route I'd have used deduction rather than inference and this post would have been called deductions & deductability. Fellow blogsmiths, learn from this tale! If you try to be clever with your posts, eventually you come unstuck!!