Here is an explanation to why Shepard is in this picture with a female reaper.
As we know, Shepard is in the galaxy-saving business only to score hot female crewmembers... But after he had slept with Ashley, Tali, Liara, Samara, Kelly, Traynor, Chakwas, asari councilor, Shiala, the consort, Aria, Nyrene, Allers, Al jilani and a ton of other women, he decided to do the impossible!
Score a reaper! So he found a female reaper and used sleek one liners to chat her up. Turns out that reaper was a big fan of Shepard, so they went for coffee. Then on a movie. Shepard took her to dinner and after about a year, Shepard married the reaper and they had reaper babies.
And they lived happily ever after XD (Or until Shepard's reaper children grow up and destroy all life...)
(Don't be offended by this stupidity. Had some time to waste, so I made up a funny story)