How to approach the composition done by one person

In this post I would like to do a little reflection on how we
approach the composition of an issue when only one person in charge
performing all the instrumentation.
First of all, I do not want to take these comments as a criticism of anyone
nor does anyone think that the Goddess Inspiration has enlightened us. Simply
is to explain what we intend to reflect in each composition.
And of course we will focus on the compositions of modern music
Another issue is the creation of classical works.
As you know, TheBertos is composed of two people, and in many
cases the compositions are made almost entirely by one of us.
In my case, I always try is to give the impression that there is a group behind.
Playing in a band or solo do much to mark the time of writing.
In one group, each member has its own personality, sound and way of understanding
music, and all that is reflected in his playing.
When I hear the songs of a solo (even people like Satriani, Vai, etc)
I finally realize that creating a base and develop the theme on it.
This base may be more or less complicated, but the end is a base
devoid of soul. Okay, okay. In this case, what prevails is the
main melody, is what they want to show.
But when your intention is to compose a group, you have
work with each instrument as if you were someone else. You should try
play different, feel the music differently. Not only sound change
or instrument. This is what we try, give a sense of group. Although
know it's complicated.
For example, in "Shut Up!" we have two guitars that never stop throughout the track.
But with each we have tried to "play" different.
While this played a more classic, no fuss, no stress.
The other is more incisive, more sharp. It takes advantage of the group to leave
details, not encased in the pattern that makes the song.
On the other hand, this bass. This covers the entire song, insistent rhythm,
just looking at the battery (which also leaves some details out the rhythm).
When I was creating the bass line I always remember Ian Hill, bass on
"Judas Priest". Does anyone remember him ? No. That's it. He was focussed on the rhythm, like he was outside the group;
while Rob Halford and guitarists gave the face.
We would like your comments and contributions to the subject
Regards
Alberto