Tsubasa: RESERVoir CHRoNiCLE, RG Veda Recommendations
the same author, lots of tragedies, a good plot, the same kind of humor, some people gets killed
Although neither explains just how it works until the end, both series are about fate, destiny, and trying to forge your own path in spite of seemingly unavoidable doom. And being from the pen of CLAMP, both series have that certain something that will leave you thinking, "Wait, what? Oh, woah."