Simon Scarrow always succeeds in letting me into his tough, male Roman world without alienating me from an environment so different from my own. His heroes, Macro, the blunt-speaking grizzled veteran, and Cato, the educated and younger soldier, bash their way through numerous adventures (including Eagle in the Sand) in the time of Emperor Claudius.

The adept/tyro dynamic twists between the pair, each learning from the other, while becoming friends, no, comrades, in the face of a series of dangers thrown at them. Yet, I identify with their values, their reasons for their decisions in an uncompromising often brutal world. But if I based my behaviour on theirs, I would end up doing twenty years in Holloway.

So, what’s going on here?

Simon Scarrow builds his world accurately and succinctly. No question. You are in the middle of a forced march, a seige in the scorching desert or emmeshed in the corrupt palace politics. You feel the bitterness of a lover killed, the conspirator escaping, the relief that you are alive after rebels and Parthians have killed many of your comrades.

And that’s the point. Scarrow builds a plausible world in meticulous detail, drawing on original sources and painstaking research. But he entices us into the parallel world of emotions experienced by Macro and Cato as human beings. Despite the alien values framework by 21st century  norms, many of their dilemmas are the same and the decisions just as difficult to make.

But what if the alien world isn’t based on history? This is both the task and a trap before science fiction, alternate history and fantasy writers. Many such worlds dip heavily into our own history, folk myths and basic fears: Tolkein used Anglo-Saxon culture for Theoden, C S Lewis used the wicked female witch versus golden, enigmatic and noble male, H G Wells despaired about our future as a race. And I’m not going to try and work out who or what the Klingons are…

The most intruiguing, for me, is the alternative history model where history changes at a point in the past and canters off in a different direction. Michael Chabon’s The Yiddish Policemen’s Union is a stylish noir murder mystery packed with pathos, wit and bizarreness set against the premise that in 1947 the Jews were given part of Alaska as their homeland instead of Palestine. But only for 50 years. And the lease is up…

The world weary detective’s character has the usual elements: failed relationships, faithful sidekick fighting to stay in the “normal” world, a tough boss (his ex-wife), a dead relative to avenge and gritty determination. But although the world-building is achieved with dense, interlocking  detail, it’s the essential shared dilemmas and emotions that bind us into this fantastical world.