After holding steady last week to avoid the dreaded Week 2 drop-off, HBO’s fantasy series Game of Thrones is starting to build. This past Sunday, its third episode drew 2.4 million viewers for its original airing at 9 PM, up from the 2.2 million who tuned in for each of the first two episodes. The combined audience for the 9 PM and 11 PM showings, 3.1 million, was also a series high.