An Aikido practitioner who wants to be able to attack comes
to mind. As we’ve mentioned before,
Aikido itself is a very pacifistic martial art, that doesn’t mean everyone who
practices it is. It’s fairly common for a martial artist to pick their first
martial art, “blind.” They like the idea of taking classes, but they don’t
really know what they’re looking for, so they’ll start with one that doesn’t
fit their outlook. Good schools and instructors should talk this
stuff through with prospective students, to determine if they’re a good fit for
the curriculum, but it doesn’t always happen.
Another possibility is that the Aikido practitioner found
themselves in a situation where their training really did not prepare them.
Again, this is pretty common, especially among martial artists from recreational backgrounds. When presented with an actual combat situation, they
aren’t ready. I suspect this is especially true with Aikido, given the martial
art has almost no margin for error, but I’m not sure.
As for where someone would run across Muay Thai? It’s all over the place. A lot of the schools that have popped up in The
States are far less vicious than the martial art’s original form, but this did
start out as a brutal, competitive martial style. It’s also possible someone who
wanted to compete in MMA may have gone from Aikido to Muay Thai.
With the practical variant of Krav Maga, the list is a lot
shorter. Israeli Defense Force veterans are the primary vector. That said, if
you’ve got a character with a background in law enforcement, or military
service, it’s possible they learned from an ex-IDF soldier.
However, Krav Maga is also one of the fastest growing
martial arts in the US. The version available to civilians hasn’t been kept up
to date (and may have been altered to make training safer, I’m unsure), but it
is fairly easy to come across if you live in a major metro area.
It’s probably worth pointing out, people don’t usually start
blending martial arts together until they’ve been practicing for a couple
decades (at least), and most never do. If they learn another martial art, some technical elements will bleed across (unintentionally), but
making the deliberate choice to take pieces of one martial art and incorporate
them into another is much more challenging than it appears. In the examples I
gave above, it’s more likely the Aikido practitioner would have abandoned that
martial art in favor of another style, rather than trying to mix them together.