David Rory books

Hi Ally, that's great to hear.
I can offer this as guidance - Most of the books share the same basic characters either as the main protagonists or supporting cast.
They are introduced in the Daniel series and they are Daniel, Lauren and Bonny. The Daniel series starts in Norn-Iron during the height of the troubles in the late seventies and introduces a deep conspiracy (Based on fact.) that haunts the three most of their lives. It follows them as they move to the UK, France and later West Cork. Daniel and Lauren are undercover intelligence officers or 'spooks' as they describe themselves, but their main enemies lie within the British establishment and security services.
These are not conventional characters and they do not subscribe to the tribal norms usual in Ireland. For that reason many Irish readers find the stories fascinating, but challenging.
The West Cork Trilogy has these three as background characters but features their children. Again the subject mater is challenging - sexual abuse in families and the clerical scandal. Hard hitting but warm human stories.
You can start anywhere and if the stories grab you then go back or forward in time to catch up with the various characters' history.

The Butterfly Effect Trilogy asks the question; how would Bonny, Lauren and Daniels' life paths been changed if one small decision had deflected them from the paths explored in the other stories.

Prairie Companions and Chepi the Butterfly Effect, are based in Canada and are very different historical stories. Many of the characters are First Nation Cree. (It is where we first meet Daniel as a 17 year old.)

That is where I would start the saga.

Like I said, none of these are conventional novels, they major on individuality and non-conventional lives. Having said that, I have many readers who get addicted once they start.