The ESA and the Japanese have a pair of orbiters sharing a ride to Mercury. Three years after launch they just did a flyby.
When I was a lad, we only had pictures of half Mercury. It was all flybys as of the early 1980s, excepting Mars. It's (much) later we got orbiters around Venus, Jupiter, Saturn. So: how come distant Saturn but not nearby Mercury? Answer to that: delta-V, bro.
Mercury is a much smaller world than Venus, and closer to the Sun. Its orbit is more inclined than Venus as well and much more elliptic. Even to orbit Venus, the Magellan required some fancy orbital manoeuvring. To be fair, the Cassini to Saturn was similar, albeit with a heavier craft.
BepiColombo has to run around the Sun five more times before it can orbit our innermost planet. Good news: that's only four years from now.
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