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Politically-speaking, I think it would be interesting if the Horses opened negotiations with the Scorpion Empire.
The Scorpions' closest holdings in the Chaine Cluster are not all that far away from the Horse OZ as of June 3152; indeed, with the Scorpions in possession of fully functional HPGs, and with the Horses fielding various technology types (such as the aforementioned QuadVees) with which to trade, the basis for an agreement well bargained and done could be cobbled together. Especially if Alaric decides he's in no hurry to un-Abjure the Scorpions, and/or to consider inviting them to sit on the new Star League Council at Unity City.
Indeed, from the Scorpion perspective, the Khan and zarKhan might open a line of communication with the Horses, even if talks with Alaric appear to go well. Best to keep one's options open, after all.
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Given the current moves by Scorpions they will be coming into contact with Horses (and Lyrans) before long so you are on to something here
Scorpions have been snooping around old territory of RWR for a century now with no indications of slowing down and the Horsies have been shacking up in the old RWR capital Apollo for a while now among other planets
It's only a matter of time before they are face to face with each other (outside earlier Seeker visits) especially once that HPG Scorpions are building in Chainelane Isles goes online and becomes talk of the town
And Horses and Scorpions have surprisingly plenty things to chat about especially in trade department and exchange of information (for Scorpions) and political experiences (for Horses)
There's also the fact that their military doctrines have more in common than most people think, while Scorpions don't go all in on combined arms approach they do maintain small but stable vehicle pool in their Touman/doctrine and a massive one in Garrison units, they can always use more quality products that Horses design
They have interesting overlap with some more obscure mechs exclusive only to two of them at this point (Wyvern IIC, UrbanMech IIC, Bowman, Thunder Stallion) while Scorpions have their own tradition of quad mechs second only to Horses themselves (Fire Scorpion, Snow Fox, Arana, Tolva, Rhino)
Horses could also use some tips from Scorpions on how to start getting some mileage out of all those locals they live next to, Horses have been solid neighbors and guardians so there's not a single reason why they shouldn't start to open up more with each other
Horses and Scorpions definitely have a lot of things to talk about, whichever upcoming book covers that part of space will most likely elaborate on it