Twitter – Tweeting to someone on NCIS without letting other people know the real name

These tweets are always public. Anyone can see them anytime. But Twitter website is not built to show @B's replies to @A on the home timeline if they are not following @A. But there are Twitter clients that does it. I remember TweetDeck having this feature. It'd show the followers of @B all of his tweets and replies to @A even if they are not following @A.

Well I think the tweets that are listed (in case of the ones of celebrities) doesn't have any particular order.

Taking this tweet as an example I think notice that most tweets that are listed either are:

1. Having a huge conversation related with them i.e many other users reply to that tweet and it's a talk(which may be off topic).
2. Have been retweeted (not always the case).
3. User who tweeted has many followers.

These were the general trends I observed in this tweet. The listing by Twitter in most cases might be in fact completely random (no concrete way of knowing).