Contributed by MelT

Many of my chile crosses in 2008/2009 were hybrids between Capsicum chinense varieties and crosses between C. frutescens "Duke Pequin" and C. chinense.  In 2009, most
of the plants in my garden were the F1 hybrids from 2008 pollinations.

Some examples:

C. frutescens "Duke Pequin" X C. chinense "Tiger Teeth"[an excellent variety collected in a market in Guyana]
Large vigorous plant in mid-season:

Detail

Unripe fruit

Comparison of ripe fruits of hybrid and parents.

"Bhut Jolokia" X "Duke Pequin"
Unripe fruit:

Ripe fruits of hybrid and parents:

Trying reciprocal hybrids [using the same two parents, but differing as to which is the "mother" and which is the pollen parent] seemed to have little effect in this case.  At
least superficially,"Duke Pequin X Bhut Jolokia" looked pretty much like "Bhut Jolokia X Duke Pequin" [the female parent is listed first in this notation].

Duke Pequin x Congo Red
Unripe fruit:

Fruits of hybrid and parents:

The ripe fruits of the above hybrids tend to soften when fully ripe, which is supposed to be a C. frutescens trait. "Duke Pequin" X C. chinense generally were large, vigorous plants, possibly even more so than "Duke Pequin".  By the end of the season the three hybrids above all approached 2m
tall.

Part of the jungle of hybrids [the garden's soil level is actually about a half meter below the pavement]

Some of the C. chinense crosses seem promising.
Tiny-fruited "Wild Brazil" X Bhut Jolokia:

The fruits were similar-looking to Duke Pequin X Bhut Jolokia, but the plants were
more moderate-sized.

Bhut Jolokia X Congo Red, showing results of reciprocal crosses. Both hybrids rather resemble
big "Trinidad Scorpion" fruits.

Congo X Tiger Teeth, with large fruits:

Another very nice cross [not shown] was Bhut Jolokia X Tiger Teeth, with large very aromatic fruits.

Crossing the mild "Aji Dulce #2" with the almost heatless "Trinidad Perfume" resulted in very productive plants with beautiful but nearly heatless fruits:

Crossing the extremely hot "Bhut Jolokia" (two fruit on the left) with the heatless
"Trinidad Perfume" (3 on right) resulted in uniformly hot F1 hybrids:

I expect that the F2 generation might produce some individuals with mild fruits. If non-pungency behaved as a simple Mendelian recessive trait, one would expect 1/4 of the F2 generation to be mild.  Although it's likely to be more complex than that, I'd be interested in trying a chile with Bhut Jolokia-like flavor but less heat.